(a) Field of the Invention
The present invention is related to a keyboard style electronic musical instrument of the waveshape memory type wherein different waveshapes read out from the memories are mixed together at a certain mixing ratio and then converted to musical sounds. More particularly, the present invention pertains to an improved electronic musical instrument of the type mentioned above, wherein the waveshape mixing ratio is variable through the touch control of the key operation done by the player of the instrument.
(b) Description of the Prior Art
In U.S. patent application Ser. No. 773,788 filed on Mar. 2, 1977 by the same assignee as that of the present application, there is proposed a keyboard style electronic musical instrument of the waveshape memory type wherein a plurality of different waveshapes are read out from a plurality of memories and then mixed together at a mixing ratio which is variable either with lapse of time or in accordance with the nature of the touch of the key depressed by the player of the instrument.
Another musical instrument of the waveshape memory type has been proposed in U.S. patent application Ser. No. 898,523 filed on Apr. 20, 1978, by the same inventors as those of the present application. In the musical instrument disclosed in this earlier application, mixing of the waveshapes read out from waveshape memories is adapted to be performed by carrying out multiplications individually for the respective retrieved waveshapes with associated time-dependent parameters and then by adding up the resultant values to obtain the aimed musical sounds.
Since, in the electronic musical instrument which was priorly proposed by the same inventors, read-only memories are read out by a constant read-out address signal, once the parameter signals which are to be memorized in these read-only memories have been determined, there will be developed variation of tone of the musical sound produced (variation of the configuration of the musical tone waveshape) always in a same pattern. Accordingly, it is not possible to control the pattern of tone variation of the musical sound produced in accordance with the nature of the touch of a finger of the player onto a key of the keyboard as is possible in a natural musical instrument.